The dot-matrix printer is the earliest form of a printer. The dot-matrix printer has advantages of simple structure and low cost. What is more important is, the dot-matrix printer is characterized by printing in an impact manner. Such a characteristic is a second-to-none choice in various printing occasions such as department stores, supermarkets, etc, in which it is needed to provide duplications.
The operation principle of the dot-matrix printer is that, a printer head drives its printer pins to impact an ink ribbon to bring the ink of the ink ribbon onto a printing medium, so as to form images and characters on the printing medium. In order to facilitate replacing the printing medium, the dot-matrix printing generally uses an “easy-paper-loading” structure. However, the “easy-paper-loading” mechanism provided in the prior art has some apparent drawbacks.
FIG. 1 is a paper-rolling printer disclosed by Chinese Patent Document CN03148992. In said printer, a fixed frame 12 supports a printer head, a movable frame 13 supports a paper supporting member 55, the movable frame 13 is hinged to the fixed frame 12 via a pivot shaft, and the movable frame 13 rotates about the pivot shaft to be opened or closed relative to the fixed frame 12. When the movable frame 13 is closed relative to the fixed frame 12, the printer head is opposite to the paper supporting member 55 to form a printing position. Along the paper-conveying direction, a first path 15 and a second path 36 are provided at downstream of the printing position, wherein the first path 15 is used for guiding printed paper 7a to be outputted from a paper exit of the printer, and the second path 36 is used for guiding an ink ribbon 9 to be conveniently placed at the printing position. In addition, said printer also comprises a pair of rollers, wherein one roller 25 is mounted in the movable frame 13, and the other roller 26 is mounted between the first path 15 and the second path 36 for outputting the printed paper from the printer. In order to facilitate bringing the ink ribbon into the printing position, a first guiding surface 27a and a second guiding surface 41a are provided at two sides of the second path 36. The disadvantage of the above invention is that, the roller 26 is provided between the first path 15 and the second path 36, directly above the printer head. Such a configuration, on one hand, hinders the smooth entry of the ink ribbon into a printing position, resulting in difficulties in replacing the ink ribbon, and on the other hand, hides the printer head to bring trouble to the cleaning and maintenance of the printer head.